<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <button id="btn">btn</button>
    <script>
        var btn=document.getElementById("btn");
        var timer=setInterval(function(){
            console.log("a")
        },1000)
        /* 清除定时器
        clearInterval() */
        console.log(timer)
        btn.conclick=function(){
            clearInterval(timer)
        }
    </script>
</body>
</html>